KH vs KHRM Motor Differences?

Racing K Models

KH vs KHRM Motor Differences?

Postby JerrryR » Sat Feb 29, 2020 4:19 pm

Hi All,
A friend of mine asked me to check on something for him. He wants to know what differences if any were there between a KH motor and a KHRM motor. Also he thinks they made some KHRMs in 1954, did they? If they did do you know if they were early or later in 54?
Thanks,
JerryR
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Re: KH vs KHRM Motor Differences?

Postby wz507 » Sat Feb 29, 2020 9:18 pm

I believe that functionally and internally the KHK and KHRM engines were essentially one and the same (std crank and rod bearings with bushed cam chest), with minor external differences. I know of a set of 1954 KHRM cases, without a trap door, so HD evidently made some early in the 1954 model year.

The link below has some good info on KHRMs.

viewtopic.php?f=5&t=761
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 1:19 am

The KHRM came out in 54. The only motor differences besides competition clearances were KR cams. Shaved cyl fins for Wico vertical mag. High pipe. Skid plate. Oil tank. Brakes raised on rear. Rear fender cut. Front fender cut. Erik Happy Leaap Day. :D
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 1:29 am

My buddy Joe RIP had one of the few in 1954. A 55 model. H-D gave it to him to play with and do press shoots after wrapping up the inaugural AMA National Championship in 1954. He also received bikes in 56 and 57 with those wins. They were only on loan for 1 year. Erik
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 1:58 am

Just spoke with my buddy Marsh, Joe's KR builder, he personally rebuilt a 54KHRM for the owner, twice in 25 years. So 54 Model YES. Erik
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Re: KH vs KHRM Motor Differences?

Postby thefrenchowl » Sun Mar 01, 2020 6:30 am

Hi,

Only diffs between 1954 KHK and 1954 KHRM are cylinders and Wico vertical magneto.

A pair of OEM std bore KHRM 1954 one year only cylinders with fins massive clearance for Wico magneto:

Image

In 1955, Wico was swapped to cheaper/smaller Fairbanks Morse, relieving was deleted as far as I know.

Patrick
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 3:57 pm

What about cams? Marsh told me they are not KHK, they are a KR grind with KHK springs and covers. Does anyone have more info on that? Erik
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 4:54 pm

This is the classic photo of Joe and his 55KHRM. November 1954 Enthusiast cover. The Kicker Arm definitely has a new twist! Special Shocks...So I run .420" Lift E cams with stock KHK spring set up no problem. Would not have been a problem for KHRM to have a cam set warmer than KHK, which is close to the first KR 45" grind. Would have had -53R set for 54 model. If it was just a no battery ignition change between KHK and KHRM why not call it a KHKM? The "R" is for race so lets get her hopped some, cams are the easiest way to "R" up. I'll go with Marsh unless someone has different documentation or info. I'm working with him on documenting, collecting 1950s AMA Dirt Track History. He raced a TT Knucklehead HardTail in AHRMA with One Leg, world wide until he turned 80. Erik
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Joe Leonard 55KHRM
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Re: KH vs KHRM Motor Differences?

Postby Simon » Sun Mar 01, 2020 11:05 pm

Whilst Marsh is not wrong, they came with KH cams or KR/KHK grind as options, as the shop dope shows timing alternatives for both. I actually bought my Wicos and many other parts from Marsh - what a great guy.
Shop dope also has wiring diagram for adding lights, as some of the races might push the rider close to evening time.
As said above, relieving on the 54 cylinders for the Wico.
My old 54 KHRM cases did not have a trapdoor.
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Re: KH vs KHRM Motor Differences?

Postby EKHKHK56 » Sun Mar 01, 2020 11:44 pm

Thats great info. The KH cams do make much better bottom end torque. Cams are always the icing on the cake, after you decide what rpms you want your power band in.
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